The purpose of this study is to determine the preferred method of fixation avoid relapse following maxillary and mandibular osteotomy to correct facial deve pmental deformities. Correlations are being established between semirigid and nonr id fixation techniques, and the degree of relapse as measured by cephalometric techniqu utilizing metallic markers implanted in the maxillae and mandible 6 months prior to o hognathic surgery. Changes in the height or the width of the attached gingiva are be g recorded. Pre and post-operative changes in facial contours and occlusion are being m sured. In addition, movements of the tongue, mandible and associated soft tissues dur g speech and swallowing are being assessed with ultrasound imaging procedures. Initial sults observed at 3, 6 and 12 months did not demonstrate a significant difference n relapse between the two groups. However, patients treated with semirigid fixation perienced better diet, speech, and oral hygiene compared to patients with rigid inter l fixation. Initial results of the swallowing tests demonstrate that maximal physical a ustment in the mandibular-hyoid relationship occurs in the first three months followin the surgery. Functional changes continue to occur throughout the year. There appears to e a positive relationship between the surgical procedure and swallowing function. Both p cedures serve to normalize the rate of swallowing, i.e. to decrease the duration of swall ing after surgery. Mandibular reduction patients were more abnormal in their pre-sur ry duration (i.e. they took longer and required more effort to swallow before surgery).